Holocene dynamics of the alpine timberline in the High Sudetes

The study focuses on the High Sudetes that represent the most distinctive islands of alpine forest-free area among hercynian mid-mountains of Central Europe. Based on data from newly taken cores and previously published pollen profiles, comparison of the development of the alpine timberline position is carried out. The first of the analysed pollen profiles — the Labsky důl core in the Krkonoše Mts spans the whole period of the Holocene, the Keprník and Mezikotlí profiles in the Hruby Jeseník Mts bring information from the Subboreal/older Subatlanticum turn to the present. An exceptional position of the Krkonoše Mts in terms of permanent presence of the alpine belt throughout the Holocene was confirmed. Three oscillations of the alpine timberline during the Lower Holocene were detected in the profile from the Labsky důl site. In the Hruby Jeseník Mts a temperature dependent forest-free area existed at least since Subboreal to the present.     

Fatigue failure of the sliding hip screw – clinical and biomechanical analysis

The study was aimed at the clinical and biomechanical analyses of the sliding hip screw breakage with the use of finite element method. We have identified two patients with the sliding screw breakage. In the first patient, the biomechanical analysis revealed the reduced stress values σ_HMH not exceeding the yield limit or strength limit of the implant. The yield limit was exceeded in second one. Clinical and biomechanical analyses have demonstrated that adherence to technical requirements of the appropriate osteosynthesis implementation is the principal condition of timely healing since it prevents the material failure.     

HLA and disease.

Many human diseases are associated with HLA class I, class II and class III antigens. It appears that the class III antigen disease associations can be explained by a direct defect operating at the level of either the class III gene or its gene product. The mechanism underlying class I and class II antigen disease associations is at present unknown. In this review we have considered thirty diseases which have been ranked according to their relative risk as defined by the frequency of a given HLA antigen in patient and control populations. The chronic inflammatory disorder, ankylosing spondylitis and its association with HLA B27 has been used as a model to study the HLA linked diseases. We have suggested that the disease may be caused by the Gram-negative microorganism Klebsiella which has antigenic similarity to HLA B27. It is proposed that some antibodies made against Klebsiella bind to HLA B27, thereby acting as autoantibodies leading to the pathological sequelae of chronic inflammatory arthritis. This is the crosstolerance hypothesis or molecular mimicry model and it has been compared to the receptor model. It is further suggested that the crosstolerance hypothesis can be utilised as a general theory to explain the association of other diseases with the class I and class II antigens, and offer a possible explanation for the polymorphism of HLA.